Process for producing granular and fibrous collagen dispersions

ABSTRACT

A collagen granule is prepared from unhaired hides by cutting the hide into long, thin strips, recutting the strips and comminuting the recut strips. Collagen fibers are prepared from the granule by shearing in a disc mill. Since no added water is required in the process, the solids content of the product is virtually the same as that of the original hide. The flexibility of the process conditions allow for the production of granules and fibers of different lengths so that collagen products can be made for incorporation into a variety of human and animal foodstuffs.

United States Patent Aceto et al. 1 May 30, 1972 s41 PROCESS FORPRODUCING [56] References Cited GRANULAR AND FIBROUS COLLAGEN UNITEDSTATES PATENTS DISPERSIONS 3,151,990 l0/l964 McKnight ..99/l76Inventors: Nlcholas C. Aceto, Roslyn; Joseph Naghskl; MichaelKomanowsky, both of Philadelphia, all of Pa.

Assignee: The United States of America as represented by the Secretaryof Agriculture Filed: Mar. 31, 1970 Appl. No.: 24,327

U.S. Cl ..146/227, 146/239, 99/176 Field of Search 146/237, 239, 240;99/176 Primary Examiner-Willie G. Abercrombie Attorney-R. Hofi'man andW. Bier ABSTRACT A collagen granule is prepared from unhaired hides bycutting the hide into long, thin strips, recutting the strips andcomminuting the recut strips. Collagen fibers are prepared from thegranule by shearing in a disc mill. Since no added water is required inthe process, the solids content of the product is virtually the same asthat of the original hide. The flexibility of the process conditionsallow for the production of granules and fibers of different lengths sothat collagen products can be made for incorporation into a variety ofhuman and animal foodstuffs.

' 2 Claims, No Drawings PROCESS FOR PRODUCING GRANULAR AND FIBROUSCOLLAGEN DISPERSIONS A non-exclusive, irrevocable, royalty-free licensein the invention herein described, throughout the world for all purposesof the United States Government, with the power to grant sublicenses forsuch purposes, is hereby granted to the Government of the United Statesof America.

This invention relates to a granular form of collagen and to collagenfibers and more particularly to dispersions of the same containing from-40 percent solids and to a process forpreparing the dispersions. I

The increased production of livestock coupled with a reduction in theprincipal market for hides and skins makes it imperative that other usesbe found for these products. To date, the use of collagen in foods hasbeen largely neglected. However, this is potentially the largest outletfor collagen, other than its use for the manufacture of leather.

Native collagen is not digested readily and is deficient in essentialamino acids. However, as a partially hydrolyzed gel it is readilydigested. In this form it can serve as a binder, wrapping or coating forother foods. The manufacture of sausage casings from collagen is anencouraging start on a food use. However, this market will take only asmall fraction of available hides to meet its requirements.Consequently, there is a need to find other uses for and to make otherproducts from the over abundance supply of hides.

There is considerable current and potential demand for collagen fiberdispersions for use in sausage casings, surgical applications, papermaking, food applications such as food binders and/or extendors,vegetable protein texturizers and as a component of high protein valuesynthetic meat. Therefore, it is essential that methods be found andproducts made from the current available hide supply to satisfy theneeds in these other applications and to utilize the over supply of hidematerial.

It is an object of this invention to process the hide to a high solidcontent dispersion with acceptable uniformity for use in other fieldsespecially in the food industry.

Another object of this invention is to prepare from the hide material agranular product which can be incorporated into food stuff for human andanimal consumption.

Still another object is to provide a means of producing a dispersion ofcollagen fibers of a preselected fiber length distribution for surgicalapplications, food additives and binders, paper fillers and othersimilar uses.

According to this invention unhaired hides were cut into long, thinstrips which were recut in a rotary knife cutter and then fed to acomminuting mill to obtain a product of desired size. An importantfeature of the process just briefly described is that the only waterpresent during the processing is that naturally present in the hidematerial. If necessary, the

. moisture content of the hide to be processed can be adjusted to anydesired level. Since all prior art methods of preparing fibrous forms ofcollagen from hide material call for the addition of relatively largeamounts of water, the process of this invention in which no added wateris required is unique.

The materials to which this process can be applied are animal hides,either grain or flesh splits or whole hides from cattle, sheep, swine,etc., which have been fleshed and unhaired, and are either fresh, or inthe lime, or washed and delimed. Limed fleshed flesh-side hide splitsare washed to remove lime and the pH is adjusted to a suitable level.Whole hides or grain-side splits can be used provided they are fleshedand unhaired in which case the hides or splits need not be washed northe pH lowered before treatment. The hides or splits are fed to a stripor rag cutter to obtain strips about onefourth to three-fourths incheswide. The strips are then put through a rotary knife cutter usingscreens with k to 1.0 inch diameter openings after which the materialfrom the rotary cutter. is fed to a comminuting mill or high-speedcuttergrinder. The comminuting mill is equipped with a means for feedingdry ice to the cutting chamber so that if it is so desired a constantcutting head temperature can be maintained. in order to avoiddenaturation of the collagen it is ofien desirable to keep the cuttinghead temperature below that at which colla en denatures.

e cutting heads on the comminuting mill range in size from 0.02 to 0.50inches so that a product, largely collagen granules, in this size rangecan be obtained without further processing. If fibers and small fiberbundles are the desired product, the collagen granules from thecomminuting mill are further processed in a revolving disc mill whichprovides the shearing action necessary to separate the granules intofibers. These operations are important because granules, fiber bundlesor fibers of any desired preselected length can be produced depending onhow or in what product they are to be utilized.

The following is an example of the process: pounds of limed fleshedflesh-side splits, washed and adjusted to pH 7, were cut in a stripcutter into strips one-fourth to three-fou rths inches wide and dividedinto two batches. The first batch was passed through a one inch screenin a rotary knife cutter while the other batch was passed through therotary knife cutter without a screen. When the two products from therotary knife cutter were passed througha 0.060 inch head of acomminuting mill operating at 5,325 r.p.m., along with sufficientpowdered dry ice to prevent denaturation, it was found that although thescreened material passed through more easily, the two products appearedidentical. The products, slurries of sharply cut, well-defined granularparticles at a solids level of about 29 percent in which the pH wasabout 7.0, showed little or no denaturation and were easily dispersedwithout clumping or aggregating. A portion of the composite product wasforce-fed to a single revolving disc mill with the plates set atapproximately a three-eighths inch clearance. The final product, about28 percent solids, consisted of a mass of fibers containing no hardgranules.

When mixed with fresh ground beef, the product of this invention,especially the collagen granules of about 0.060 inches, helped to retainweight, prevented loss of juices and reduced shrinkage during frying orbaking. Collagen granules at the 0.060 inch size were not detectablewhen the product in which the granules were incorporated was masticated.

We claim:

1. A process for the preparation of high-solids dispersions ofundenatured collagen granules and high-solids dispersions of undenaturedcollagen fibers, comprising:

a. cutting unhaired hides into strips from 0.25 to 0.75 inches wide;

b. recutting said strips in a rotary knife cutter into pieces not longerthan about one inch in length;

c. comminuting said recut strips through a cutting head having uniformdiameter openings, said openings ranging in size from 0.02 to 0.50inches, said comminuting being done at a temperature low enough toprevent denaturation of the collagen and in the presence of only thatmoisture present in the uncut hide material to obtain at this stage adispersion of collagen granules containing about 15 to 40 percentsolids; and

d. shearing said dispersion of collagen granules in a revolving discmill to obtain a dispersion of collagen fibers containing about 15 to 40percent solids.

2. The process of claim 1 wherein the comminuting is done in thepresence of dry ice.

2. The process of claim 1 wherein the comminuting is done in thepresence of dry ice.